Machine translation (MT) concerns the automatic translation of natural language sentences from a first language (e.g., French) into another language (e.g., English). Systems that perform MT techniques are said to “decode” the source language into the target language.
Roughly speaking, statistical machine translation (SMT) divides the task of translation into two steps: a word-level translation model and a model for word reordering during the translation process. The statistical models may be trained on parallel corpora. Parallel corpora contain large amounts of text in one language along with their translation in another. Unfortunately, such corpora are available only in limited amounts and cover only in specific genres (Canadian politics, Hong Kong laws, etc). However, monolingual texts exist in higher quantities and in many domains and languages. The availability of monolingual corpora has been enhanced greatly due to the digital revolution and wide-spread use of the World Wide Web. Methods for processing such resources can therefore greatly benefit the field.